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Two things:
Can anyone verify that XNU actually stands for XNU's Not Unix ("is" probably shouldn't be listed as its own word of it would be XINU)? Most references on the Internet seem to be speculation (or speculation repeated as fact). —The preceding unsigned comment was added by 63.227.67.1 ( talk • contribs) 21:23, 15 July 2005 (UTC)
Mac OS X was originally populated with mostly NetBSD userland. It wasn't heavily moved to FreeBSD until later (I suspect once Jordan Hubbard was brought into Apple from the FreeBSD project). —The preceding unsigned comment was added by 68.158.68.247 ( talk • contribs) 5:39, 20 February 2007 (UTC).
Seconded. Wilfredo Sanchez was a NetBSD developer for a while synching the userland trees between Darwin and NetBSD. NetBSD's portability made it easier for Apple to get a current userland (instead of the crufty NeXT/Rhapsody one). The move to FreeBSD was only AFTER Jordan was on-board at Apple and was in a management position. Because of the incestuous nature of BSDs, the differences in userlands are generally innocuous. 71.12.163.234 ( talk) 11:46, 28 October 2010 (UTC)
The article now states: "Currently, XNU runs on x86 (Intel and AMD) and PowerPC based processors...". Didn't Apple also have to port XNU to the ARM architecture, in order to get a trimmed down OS X to run on the iPhone (which appears to be ARM-based)? -- Georgeryp 03:54, 7 September 2007 (UTC)
i appreciate the limited mention of user space drivers, but would appreciate a bit more info. kernel space drivers are mentioned, as is the possibility of writing user space drivers, but no actual user space drivers are mentioned. are there any? are there likely to be any?
this is supposedly an architectural advantage, so whether it actually pays off in practice is significant. —Preceding unsigned comment added by 69.253.239.161 ( talk) 17:59, 15 May 2008 (UTC)
some discussion of performance compared with other operating systems as well as how well xnu scales when deployed on multiple cores or processors would be welcome. —Preceding unsigned comment added by 69.253.239.161 ( talk) 19:34, 15 May 2008 (UTC)
Which is correct? Zee-New or X-N-U? -- 76.100.200.168 ( talk) 03:03, 25 July 2008 (UTC)
Ex-Enn-You - Apple aren't Xenu fans ;) —Preceding unsigned comment added by 88.107.165.198 ( talk) 10:19, 5 February 2009 (UTC)
It's meant to be part of a joke, as in "what's XNU?" — Preceding unsigned comment added by OMPIRE ( talk • contribs) 20:55, 7 May 2014 (UTC)
Mach message passing is pretty well documented elsewhere but how it works in XNU seems a bit mysterious. How much of the Mach Microkernel's communication protocol is maintained? —Preceding unsigned comment added by 69.136.108.216 ( talk) 17:04, 2 March 2009 (UTC)
Does the kernel contain any AT&T/Novell or CMU copyrighted code. If so, was a license purchased outright? If not, when was it purged? -- Beland ( talk) 15:29, 6 March 2009 (UTC)
Over and above the issues brought up in the comment for the edit removing the "Reception" section, the article that section cited isn't really a very good review - it's a speculative comment about what the author thought was one particular aspect of XNU. And, while he was criticizing Mach for "[putting] anything that accesses hardware into the microkernel", he was also criticizing microkernels for all the context switches between user processes that they require. XNU not only puts network and storage drivers in the kernel, it also puts the stuff that calls the network and storage drivers - file systems and networking stacks up to the transport layer - into the kernel. That's why it's sometimes labeled a hybrid kernel, although a certain other Linux fan considers "hybrid kernels" to just be marketing.
So I'd say the removal of that section, in the state it was in, was no loss. Guy Harris ( talk) 18:34, 16 July 2015 (UTC)
Is it really true that "K32 can run 64-bit applications"?
Can we please have a citation for this surprising claim?
With other operating systems such as Linux and Windows, a 32-bit kernel cannot run 64-bit executables. — Preceding unsigned comment added by 61.68.87.30 ( talk • contribs) 06:30, 4 July 2017 (UTC)
Finally, this is worth repeating: please keep in mind that you do not need to run the 64-bit kernel in order to run 64-bit applications or install more than 4GB of RAM in your Mac. Applications run just fine in 64-bit mode on top of the 32-bit kernel, and even in earlier versions of Mac OS X it's been possible to install and take advantage of much more than 4GB of RAM.
In many documents, like this one, Apple's own kernel engineers flatly state that XNU is not a hybrid kernel: " xnu is not a traditional microkernel as its Mach heritage might imply... the kernel is in fact monolithic". To implement that, "... message passing was short circuited by having BSD directly call Mach functions"
This article states it is a hybrid. Unless I am mistaken, that is not the case. In the article on hybrids, much of the operating system still contains items that have been moved from kernel space to user space, like the file system. I believe all of these are in kernel space in XNU, and the appropriate diagram is the one on the left.
Thoughts?
Maury Markowitz ( talk) 15:25, 6 June 2024 (UTC)
References
As to the whole "hybrid kernel" thing - it's just marketing. It's "Oh, those microkernels had good PR, how can we try to get good PR for our working kernel? Oh, I know, let's use a cool name and try to imply that it has all the PR advantages that that other system has.
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
Two things:
Can anyone verify that XNU actually stands for XNU's Not Unix ("is" probably shouldn't be listed as its own word of it would be XINU)? Most references on the Internet seem to be speculation (or speculation repeated as fact). —The preceding unsigned comment was added by 63.227.67.1 ( talk • contribs) 21:23, 15 July 2005 (UTC)
Mac OS X was originally populated with mostly NetBSD userland. It wasn't heavily moved to FreeBSD until later (I suspect once Jordan Hubbard was brought into Apple from the FreeBSD project). —The preceding unsigned comment was added by 68.158.68.247 ( talk • contribs) 5:39, 20 February 2007 (UTC).
Seconded. Wilfredo Sanchez was a NetBSD developer for a while synching the userland trees between Darwin and NetBSD. NetBSD's portability made it easier for Apple to get a current userland (instead of the crufty NeXT/Rhapsody one). The move to FreeBSD was only AFTER Jordan was on-board at Apple and was in a management position. Because of the incestuous nature of BSDs, the differences in userlands are generally innocuous. 71.12.163.234 ( talk) 11:46, 28 October 2010 (UTC)
The article now states: "Currently, XNU runs on x86 (Intel and AMD) and PowerPC based processors...". Didn't Apple also have to port XNU to the ARM architecture, in order to get a trimmed down OS X to run on the iPhone (which appears to be ARM-based)? -- Georgeryp 03:54, 7 September 2007 (UTC)
i appreciate the limited mention of user space drivers, but would appreciate a bit more info. kernel space drivers are mentioned, as is the possibility of writing user space drivers, but no actual user space drivers are mentioned. are there any? are there likely to be any?
this is supposedly an architectural advantage, so whether it actually pays off in practice is significant. —Preceding unsigned comment added by 69.253.239.161 ( talk) 17:59, 15 May 2008 (UTC)
some discussion of performance compared with other operating systems as well as how well xnu scales when deployed on multiple cores or processors would be welcome. —Preceding unsigned comment added by 69.253.239.161 ( talk) 19:34, 15 May 2008 (UTC)
Which is correct? Zee-New or X-N-U? -- 76.100.200.168 ( talk) 03:03, 25 July 2008 (UTC)
Ex-Enn-You - Apple aren't Xenu fans ;) —Preceding unsigned comment added by 88.107.165.198 ( talk) 10:19, 5 February 2009 (UTC)
It's meant to be part of a joke, as in "what's XNU?" — Preceding unsigned comment added by OMPIRE ( talk • contribs) 20:55, 7 May 2014 (UTC)
Mach message passing is pretty well documented elsewhere but how it works in XNU seems a bit mysterious. How much of the Mach Microkernel's communication protocol is maintained? —Preceding unsigned comment added by 69.136.108.216 ( talk) 17:04, 2 March 2009 (UTC)
Does the kernel contain any AT&T/Novell or CMU copyrighted code. If so, was a license purchased outright? If not, when was it purged? -- Beland ( talk) 15:29, 6 March 2009 (UTC)
Over and above the issues brought up in the comment for the edit removing the "Reception" section, the article that section cited isn't really a very good review - it's a speculative comment about what the author thought was one particular aspect of XNU. And, while he was criticizing Mach for "[putting] anything that accesses hardware into the microkernel", he was also criticizing microkernels for all the context switches between user processes that they require. XNU not only puts network and storage drivers in the kernel, it also puts the stuff that calls the network and storage drivers - file systems and networking stacks up to the transport layer - into the kernel. That's why it's sometimes labeled a hybrid kernel, although a certain other Linux fan considers "hybrid kernels" to just be marketing.
So I'd say the removal of that section, in the state it was in, was no loss. Guy Harris ( talk) 18:34, 16 July 2015 (UTC)
Is it really true that "K32 can run 64-bit applications"?
Can we please have a citation for this surprising claim?
With other operating systems such as Linux and Windows, a 32-bit kernel cannot run 64-bit executables. — Preceding unsigned comment added by 61.68.87.30 ( talk • contribs) 06:30, 4 July 2017 (UTC)
Finally, this is worth repeating: please keep in mind that you do not need to run the 64-bit kernel in order to run 64-bit applications or install more than 4GB of RAM in your Mac. Applications run just fine in 64-bit mode on top of the 32-bit kernel, and even in earlier versions of Mac OS X it's been possible to install and take advantage of much more than 4GB of RAM.
In many documents, like this one, Apple's own kernel engineers flatly state that XNU is not a hybrid kernel: " xnu is not a traditional microkernel as its Mach heritage might imply... the kernel is in fact monolithic". To implement that, "... message passing was short circuited by having BSD directly call Mach functions"
This article states it is a hybrid. Unless I am mistaken, that is not the case. In the article on hybrids, much of the operating system still contains items that have been moved from kernel space to user space, like the file system. I believe all of these are in kernel space in XNU, and the appropriate diagram is the one on the left.
Thoughts?
Maury Markowitz ( talk) 15:25, 6 June 2024 (UTC)
References
As to the whole "hybrid kernel" thing - it's just marketing. It's "Oh, those microkernels had good PR, how can we try to get good PR for our working kernel? Oh, I know, let's use a cool name and try to imply that it has all the PR advantages that that other system has.